A wintry mix is a complex weather phenomenon that occurs when multiple forms of winter precipitation—such as snow, sleet, and freezing rain—fall simultaneously or in quick succession. This happens because temperatures vary at different altitudes in the atmosphere. Snowflakes may partially melt as they descend through a layer of warmer air, then refreeze into ice pellets (sleet) when they encounter a colder layer closer to the ground. Alternatively, if the warm layer is more extensive, the snowflakes may melt completely and then freeze upon contact with surfaces that are below freezing, resulting in a coating of glaze ice.